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Full text of "The Morphology And Evolution Of The Apes And Man"

LEMUROIDEA                             19
. Between the upper incisor teeth there is a well-marked gap in Lemur, but not in Chiromys. The lower canine tooth is like an incisor, and the first lower pre-molar resembles a canine tooth.
The frontal bones are frequently, but not always, separated by a persistent suture.
Vertebral Column,—When the column is examined as a whole it is seen that the tenth dorsal spine acts as a point towards which the other spinous processes converge ; and it is known as the anticlinal vertebra or
centre of motion.    Such a condition is found in many
«.
mammals, but is absent in the Anthropoid Apes and Man. The whole curvature of the spine is also similar to that of other quadrupeds.
The spinal column in a true Lemur is composed of 7 cervical, 12 dorsal, 7 lumbar, 3 sacral and 27 caudal vertebrae, or 56 vertebrae in all. The spine of the axis is very large as in many lower mammals.
Pelvis.—The innominate bones are long and narrow, with small ischial tuberosities and a short symphysis pubis. The thyroid foramen is large, and the pelvic brim is nearly circular, as in Man, but not in the Apes.
The sternum is a long, narrow rod consisting of five pieces. The clavicles are well developed, and the humerus has a prominent pectoral crest: it is perforated by a foramen above the internal epicondyle as in the Garnivora.* The radius and ulna are not anchvlosed. There is a sesamoid bone above the pisiform as in th
Gibbon and some Chimpanzees; and a radial sesai>&ad
serted
* This foramen transmits the median nerve, with or witl" brachial artery in the Carnivora.    It is sometimes present" to  tne